With the current awareness of global warming and the human impact upon the environment, there is an increasing shift towards greener, ecologically-friendly technologies. While fossil fuel-fired and nuclear power plants have been standard methods of power generation for the last century, alternative methods for power generation, particularly from renewable energy sources such as the sun and wind have been attracting increasing attention from industry, governments and the general public.
Modern windmills for power generation, or wind turbines, are growing in popularity, with wind farms being established in many countries around the world. Modern windmills come in a variety of sizes and configurations, but many people associate them with the large horizontal wind turbines used for large scale energy generation. These large turbines can stand as tall as 90 meters, with generally three equidistantly spaced blades measuring upwards of 30 meters each. As more of these three-bladed wind turbines, large and small, are being installed, there have been complaints about the electromagnetic resonance being emitted from them, generally attributed to the imbalance of the wind blades.
At the same time, there is growing interest for smaller turbine units (e.g. 3 kW to 99 kW) that are better suited to urban and residential application. In general, when wind turbines operate at low rotational velocities, imbalances become more pronounced. The resulting electromagnetic resonance and white noise levels become irritants to those living in the vicinity of wind turbines. As a result, these factors have been a source of contention among opponents and supporters of renewable energy. Addressing these factors will facilitate the development of this important market so that electricity will be generated on-site close to the electricity users. In addition, it is important that the blades used for wind capture are accurately balanced, so as to avoid potentially destructive vibration in the turbine unit.